Bug 1592488 - P9. Make a DOMCacheThread an AbstractThread. r=baku

This is a step towards bug 1119864. However, at this stage we only need the cache thread to support direct task dispatch so that we can have IPDL MozPromise acting in a similar fashion to JS promise.

Differential Revision: https://phabricator.services.mozilla.com/D74637

dom/cache/Manager.cpp

@@ -6,6 +6,7 @@
 
 #include "mozilla/dom/cache/Manager.h"
 
+#include "mozilla/AbstractThread.h"
 #include "mozilla/AutoRestore.h"
 #include "mozilla/Mutex.h"
 #include "mozilla/StaticMutex.h"
@@ -25,7 +26,7 @@
 #include "nsIInputStream.h"
 #include "nsID.h"
 #include "nsIFile.h"
-#include "nsIThread.h"
+#include "nsISerialEventTarget.h"
 #include "nsThreadUtils.h"
 #include "nsTObserverArray.h"
 #include "QuotaClientImpl.h"
@@ -251,8 +252,11 @@ class Manager::Factory {
         return Err(rv);
       }
 
-      ref = MakeSafeRefPtr<Manager>(aManagerId.clonePtr(), ioThread,
-                                    ConstructorGuard{});
+      ref = MakeSafeRefPtr<Manager>(
+          aManagerId.clonePtr(),
+          AbstractThread::CreateXPCOMThreadWrapper(
+              ioThread, false /* aRequireTailDispatch */),
+          ConstructorGuard{});
 
       // There may be an old manager for this origin in the process of
       // cleaning up.  We need to tell the new manager about this so
@@ -1887,7 +1891,8 @@ void Manager::ExecutePutAll(
   pinnedContext->Dispatch(action);
 }
 
-Manager::Manager(SafeRefPtr<ManagerId> aManagerId, nsIThread* aIOThread,
+Manager::Manager(SafeRefPtr<ManagerId> aManagerId,
+                 already_AddRefed<nsISerialEventTarget> aIOThread,
                  const ConstructorGuard&)
     : mManagerId(std::move(aManagerId)),
       mIOThread(aIOThread),
@@ -1902,14 +1907,6 @@ Manager::~Manager() {
   NS_ASSERT_OWNINGTHREAD(Manager);
   MOZ_DIAGNOSTIC_ASSERT(mState == Closing);
   MOZ_DIAGNOSTIC_ASSERT(!mContext);
-
-  nsCOMPtr<nsIThread> ioThread;
-  mIOThread.swap(ioThread);
-
-  // Don't spin the event loop in the destructor waiting for the thread to
-  // shutdown.  Defer this to the main thread, instead.
-  MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(NewRunnableMethod(
-      "nsIThread::AsyncShutdown", ioThread, &nsIThread::AsyncShutdown)));
 }
 
 void Manager::Init(Maybe<Manager&> aOldManager) {
@@ -1920,7 +1917,7 @@ void Manager::Init(Maybe<Manager&> aOldManager) {
   // Context goes away.
   RefPtr<Action> setupAction = new SetupAction();
   SafeRefPtr<Context> ref = Context::Create(
-      SafeRefPtrFromThis(), mIOThread->SerialEventTarget(), setupAction,
+      SafeRefPtrFromThis(), mIOThread, setupAction,
       aOldManager ? SomeRef(*aOldManager->mContext) : Nothing());
   mContext = ref.unsafeGetRawPtr();
 }

dom/cache/Manager.h

@@ -16,7 +16,7 @@
 #include "nsTArray.h"
 
 class nsIInputStream;
-class nsIThread;
+class nsISerialEventTarget;
 
 namespace mozilla {
 
@@ -213,7 +213,7 @@ class Manager final : public SafeRefCounted<Manager> {
   void MaybeAllowContextToClose();
 
   SafeRefPtr<ManagerId> mManagerId;
-  nsCOMPtr<nsIThread> mIOThread;
+  nsCOMPtr<nsISerialEventTarget> mIOThread;
 
   // Weak reference cleared by RemoveContext() in Context destructor.
   Context* MOZ_NON_OWNING_REF mContext;
@@ -270,7 +270,8 @@ class Manager final : public SafeRefCounted<Manager> {
   struct ConstructorGuard {};
 
  public:
-  Manager(SafeRefPtr<ManagerId> aManagerId, nsIThread* aIOThread,
+  Manager(SafeRefPtr<ManagerId> aManagerId,
+          already_AddRefed<nsISerialEventTarget> aIOThread,
           const ConstructorGuard&);
   ~Manager();